Its difficult to name one place. Because there are so many beautiful and worth seeing places in India. It depends on your interest---if you are interested in art and architecture, there are historical places, such as Rajasthan, Gujarat, Agra, the unmatched temples of Southern India.
If you like to visit Sea beaches, India has a long coast line. You can visit Goa, Mumbai, Kerala, Tamil Nadu.
If you like hill stations, you can go to Shimla, Darjeeling, Kulu-Manali, Jammu-Kashmir, Ooty or the Wonderful North East.
You also have the option to visit modern cities such as New Delhi, Mumbai, Bangalore, Hyderabad etc.
India is a unique country and it should be visited keeping that in mind--- for its rich tradition and culture, its friendly and hospitable people.